Rework -fno-omit-frame-pointer support on i386

Commit 6b1df8b27f fixed the -OS build issue on i386 (BZ#20729) by
expliciting disabling frame pointer (-fomit-frame-pointer) on the
faulty objects.  Although it does fix the issue, it is a subpar
workaround that adds complexity in build process (a rule for each
object to add the required compiler option and pontentially more
rules for objects that call {INLINE,INTERNAL}_SYSCALL) and does not
allow the implementations to get all the possible debug/calltrack
information possible (used mainly in debuggers and performance
measurement tools).

This patch fixes it by adding an explicit configure check to see
if -fno-omit-frame-pointer is set and to act accordingly (set or
not OPTIMIZE_FOR_GCC_5).  The make rules is simplified and only
one is required: to add libc-do-syscall on loader due mmap
(which will be empty anyway for default build with
-fomit-frame-pointer).

Checked on i386-linux-gnu with GCC 6.2.1 with CFLAGS sets as
'-Os', '-O2 -fno-omit-frame-pointer', and '-O2 -fomit-frame-pointer'.
For '-Os' the testsuite issues described by BZ#19463 and BZ#15105
still applied.

It fixes BZ #21029, although it is marked as duplicated of #20729
(I reopened to track this cleanup).

	[BZ #21029]
	* config.h.in [CAN_USE_REGISTER_ASM_EBP]: New define.
	* sysdeps/unix/sysv/linux/i386/Makefile
	[$(subdir) = elf] (sysdep-dl-routines): Add libc-do-syscall.
	(uses-6-syscall-arguments): Remove.
	[$(subdir) = misc] (CFLAGS-epoll_pwait.o): Likewise.
	[$(subdir) = misc] (CFLAGS-epoll_pwait.os): Likewise.
	[$(subdir) = misc] (CFLAGS-mmap.o): Likewise.
	[$(subdir) = misc] (CFLAGS-mmap.os): Likewise.
	[$(subdir) = misc] (CFLAGS-mmap64.o): Likewise.
	[$(subdir) = misc] (CFLAGS-mmap64.os): Likewise.
	[$(subdir) = misc] (CFLAGS-pselect.o): Likewise.
	[$(subdir) = misc] (cflags-pselect.o): Likewise.
	[$(subdir) = misc] (cflags-pselect.os): Likewise.
	[$(subdir) = misc] (cflags-rtld-mmap.os): Likewise.
	[$(subdir) = sysvipc] (cflags-semtimedop.o): Likewise.
	[$(subdir) = sysvipc] (cflags-semtimedop.os): Likewise.
	[$(subdir) = io] (CFLAGS-posix_fadvise64.o): Likewise.
	[$(subdir) = io] (CFLAGS-posix_fadvise64.os): Likewise.
	[$(subdir) = io] (CFLAGS-posix_fallocate.o): Likewise.
	[$(subdir) = io] (CFLAGS-posix_fallocate.os): Likewise.
	[$(subdir) = io] (CFLAGS-posix_fallocate64.o): Likewise.
	[$(subdir) = io] (CFLAGS-posix_fallocate64.os): Likewise.
	[$(subdir) = io] (CFLAGS-sync_file_range.o): Likewise.
	[$(subdir) = io] (CFLAGS-sync_file_range.os): Likewise.
	[$(subdir) = io] (CFLAGS-fallocate.o): Likewise.
	[$(subdir) = io] (CFLAGS-fallocate.os): Likewise.
	[$(subdir) = io] (CFLAGS-fallocate64.o): Likewise.
	[$(subdir) = io] (CFLAGS-fallocate64.os): Likewise.
	[$(subdir) = nptl] (CFLAGS-pthread_rwlock_timedrdlock.o):
	Likewise.
	[$(subdir) = nptl] (CFLAGS-pthread_rwlock_timedrdlock.os):
	Likewise.
	[$(subdir) = nptl] (CFLAGS-pthread_rwlock_timedrwlock.o):
	Likewise.
	[$(subdir) = nptl] (CFLAGS-pthread_rwlock_timedrwlock.os):
	Likewise.
	[$(subdir) = nptl] (CFLAGS-sem_wait.o): Likewise.
	[$(subdir) = nptl] (CFLAGS-sem_wait.os): Likewise.
	[$(subdir) = nptl] (CFLAGS-sem_timedwait.o): Likewise.
	[$(subdir) = nptl] (CFLAGS-sem_timedwait.os): Likewise.
	* sysdeps/unix/sysv/linux/i386/configure.ac: Add check if compiler allows
	ebp on inline assembly.
	* sysdeps/unix/sysv/linux/i386/configure: Regenerate.
	* sysdeps/unix/sysv/linux/i386/sysdep.h (OPTIMIZE_FOR_GCC_5):
	Set if CAN_USE_REGISTER_ASM_EBP is set.
	(check_consistency): Likewise.

1 files changed, 4 insertions, 0 deletions

diff --git a/config.h.in b/config.h.in
index 7bfe923c06..fb2cc51c03 100644
--- a/config.h.in
+++ b/config.h.in
@@ -259,4 +259,8 @@
 /* Build glibc with tunables support.  */
 #define HAVE_TUNABLES 0
 
+/* Some compiler options may now allow to use ebp in __asm__ (used mainly
+   in i386 6 argument syscall issue).  */
+#define CAN_USE_REGISTER_ASM_EBP 0
+
 #endif